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kragzy
Joined: 01 May 2007
Posts: 112
Location: Australia
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 Posted: Tue Nov 04, 2008 12:32 am Post subject: Nov 4 VH |
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OK, what am I missing? There must be a hidden pair or something in there, but I can't see it. All my usual approaches have failed.
| Code: |
+-----------------+--------+-----------------+
| 3 479 46 | 5 2 1 | 48 4679 468 |
| 2456 245 1246 | 7 9 8 | 1345 13456 1346 |
| 57 8 19 | 6 4 3 | 159 2 17 |
+-----------------+--------+-----------------+
| 9 6 5 | 3 18 2 | 7 14 148 |
| 1 34 348 | 9 7 6 | 358 35 2 |
| 28 23 7 | 4 18 5 | 6 13 9 |
+-----------------+--------+-----------------+
| 67 1 369 | 2 5 4 | 39 8 367 |
| 24568 2457 2468 | 1 3 9 | 24 467 46 |
| 24 2349 234 | 8 6 7 | 1234 1349 5 |
+-----------------+--------+-----------------+
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Cheers,
kragzy |
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crunched
Joined: 05 Feb 2008
Posts: 168
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| Posted: Tue Nov 04, 2008 2:06 am Post subject: Re: Nov 4 VH |
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| kragzy wrote: | OK, what am I missing? There must be a hidden pair or something in there, but I can't see it. All my usual approaches have failed.
| Code: |
+-----------------+--------+-----------------+
| 3 479 46 | 5 2 1 | 48 4679 468 |
| 2456 245 1246 | 7 9 8 | 1345 13456 1346 |
| 57 8 19 | 6 4 3 | 159 2 17 |
+-----------------+--------+-----------------+
| 9 6 5 | 3 18 2 | 7 14 148 |
| 1 34 348 | 9 7 6 | 358 35 2 |
| 28 23 7 | 4 18 5 | 6 13 9 |
+-----------------+--------+-----------------+
| 67 1 369 | 2 5 4 | 39 8 367 |
| 24568 2457 2468 | 1 3 9 | 24 467 46 |
| 24 2349 234 | 8 6 7 | 1234 1349 5 |
+-----------------+--------+-----------------+
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Hint:>>> Try a naked triple
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I thought this was a toughie too. See hint above.
Last edited by crunched on Tue Nov 04, 2008 2:10 am; edited 1 time in total |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Tue Nov 04, 2008 2:10 am Post subject: Re: Nov 4 VH |
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| kragzy wrote: | OK, what am I missing? There must be a hidden pair or something in there, but I can't see it. All my usual approaches have failed.
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There's a Naked Triple/Hidden Pair in [r1]. After that, an (XY-Wing) cracks the puzzle. |
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kragzy
Joined: 01 May 2007
Posts: 112
Location: Australia
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| Posted: Tue Nov 04, 2008 4:31 am Post subject: |
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Ahhhhhhhh, 468. I knew it had to be in there somewhere.
Many thanks. |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Tue Nov 04, 2008 6:56 am Post subject: |
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After the x-wings in 7 (rows 3 and 7) and 9 (also rows 3 and 7),
an xy-wing 19-17-79 in row 3 / box 3. |
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sdq_pete
Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL
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| Posted: Tue Nov 04, 2008 12:35 pm Post subject: |
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This one was for me unusual in that I came across two X-wings whilst still filling in candidates. And these two X-wings proved to be enough (indeed on 7 and 9).
Peter |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Tue Nov 04, 2008 8:45 pm Post subject: |
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| sdq_pete wrote: | | these two X-wings proved to be enough (indeed on 7 and 9). |
Peter,
you must have done some more magic ...
After basics and the x-wings, this is where something else is needed (e.g. the xy-wing)
| Code: |
+--------------------------+--------------------------+--------------------------+
| 3 79 46 | 5 2 1 | 48 79 468 |
| 2456 245 1246 | 7 9 8 | 1345 13456 1346 |
| 57 8 19 | 6 4 3 | 159 2 17 |
+--------------------------+--------------------------+--------------------------+
| 9 6 5 | 3 18 2 | 7 14 148 |
| 1 34 348 | 9 7 6 | 358 35 2 |
| 28 23 7 | 4 18 5 | 6 13 9 |
+--------------------------+--------------------------+--------------------------+
| 67 1 369 | 2 5 4 | 39 8 367 |
| 24568 2457 2468 | 1 3 9 | 24 467 46 |
| 24 2349 234 | 8 6 7 | 1234 1349 5 |
+--------------------------+--------------------------+--------------------------+
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Tue Nov 04, 2008 10:18 pm Post subject: |
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This is the way the "Very Hards" should be. I used x-wings which perhaps weren't needed - and finished off with an xy wing.
The thing is - I enjoyed doing it - no obvious one step solutions - and no Methulsa transported chains or whatever. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Wed Nov 05, 2008 2:18 am Post subject: |
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| cgordon wrote: | This is the way the "Very Hards" should be. I used x-wings which perhaps weren't needed - and finished off with an xy wing.
The thing is - I enjoyed doing it - no obvious one step solutions - and no Methulsa transported chains or whatever. |
Well, then, this will be right up your alley:
http://www.dailysudoku.com/sudoku/forums/viewtopic.php?p=14081
Keith |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Wed Nov 05, 2008 2:55 pm Post subject: |
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Definitely up my alley! Difficult but not dangerous. Highly recommended for those waiting for their next “very hard”.
Craig |
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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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| Posted: Wed Nov 05, 2008 3:14 pm Post subject: nothing more complicated ? |
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| cgordon wrote: | This is the way the "Very Hards" should be. I used x-wings which perhaps weren't needed - and finished off with an xy wing.
The thing is - I enjoyed doing it - no obvious one step solutions - and no Methulsa transported chains or whatever. |
Shortly before I spotted the X wings (as described by Nataraj) I had achieved the same resulat in a far more complicated way Er in Box 1 and the strong links in 7 and 9 created the eliminations adequate to reveal the XY wing. So why do it simply when there is a more complex way of do it?! |
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sdq_pete
Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL
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| Posted: Sat Nov 08, 2008 12:04 pm Post subject: |
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| nataraj wrote: |
Peter,
you must have done some more magic ...
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I finally found time to look at it again; anyhow, I don't know how I did it before  It frequently seems to happen in this forum that someone reports solving a puzzle without "advanced techniques" - to find the feat non-repeatable. It's a bit like discovering cold fusion I suppose - hmmm... how did I do it?
Peter |
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